The present invention relates to a manual precompression pump for spraying or dispensing a fluid such as a liquid or a semi-liquid substance, e.g. a perfume, a cosmetic, or a pharmaceutical.
Accompanying FIG. 1 shows one example of such a pump, disclosed in particular in French patents Nos. 2 305 241 and 2 314 772, and in U.S. Pat. No. 4 025 046. The pump comprises a hollow pump body 1 having an axis of revolution, provided with an annular bottom 1a pierced by a central orifice 1b and extended externally by a cylindrical side wall which extends vertically upwards to a top end. A narrower tubular portion 1c extends vertically downwards from the bottom 1a, and a tubular endpiece 4 extends vertically upwards from said bottom 1a to a top end of said endpiece 4. The diameter and the height of the endpiece 4 are smaller than the diameter and the height respectively of the side wall of the pump body.
The pump body 1 is mounted in the neck of a receptacle (not shown) containing a substance to be sprayed or dispensed, and it is fixed therein by any appropriate means, e.g. using a crimped metal capsule. The narrower tubular portion 1c is situated inside the receptacle and a dip tube 5 may optionally be fitted in said tubular portion 1c.
A piston 2 is slidably mounted inside the pump body 1. The piston 2 is hollow and shares the same axis of revolution as the pump body 1. The piston 2 preferably includes at least one outer peripheral sealing lip 2a bearing resiliently against the cylindrical side wall of the pump body 1. The piston is extended vertically upwards by a hollow rod 3 to a top end of said rod. The rod 3 includes a central channel 3a which extends from a bottom end of said channel to the top end of the rod.
The pump further includes a valve member 6 likewise sharing the same axis of revolution as the pump body 1. The valve member 6 comprises a plug 7 for closing the bottom end of the channel 3a which forms a seat 7a for the plug, and a cylindrical skirt 8 extending vertically downwards to a bottom end, said skirt 8 being capable of fitting over the tubular endpiece 4 of the pump body. The skirt 8 is guided in its motion by vertical outer ribs 8a sliding against the side wall of the pump body. Advantageously the bottom end of the skirt includes an inside peripheral sealing lip 8b to seal against the tubular endpiece 4 when the skirt is fitted over said endpiece 4. The pump is closed by an added ferrule, 11 with the hollow rod 3 sliding therein, and which is fixed to the pump body, for example by ultrasonic welding or by some other conventional means. The ferrule 11 thus constitutes a top abutment for the motion of the piston inside the pump body. At rest, the spring urges the piston against the ferrule 11 via the plug 7. In this position, the skirt 8 of the valve is disengaged from the tubular endpiece 4 so that an annular passage 13 is opened between these two parts.
The pump constituted in this manner delimits a pump chamber 12 between the tubular endpiece 4 and the side wall of the pump body 1. To explain the operation of the pump it is assumed that the pump chamber is full of the substance to be dispensed or sprayed.
When the user presses down the rod 3, generally by means of a pushbutton (not shown), the piston 2 moves down inside the pump body taking the valve member 6 with it against the thrust of the spring 10. During this downwards motion, the skirt 8 fits over the tubular endpiece 4 thereby closing the annular passage 13, and thus isolating the pump chamber 12.
The downwards motion of the piston tends to reduce the volume of the pump chamber 12. However since the liquid or semi-liquid substance contained therein is incompressible, this motion rapidly causes the pressure to increase in said pump chamber, with said pressure exerting downwards action on the valve member 6. When the pressure inside the pump chamber is sufficient to counterbalance the thrust from the spring 10, the plug 7 of the valve member 6 moves away from its seat 7a, thereby opening a passage from the pump chamber 12 towards the channel 3a in the rod. The substance contained in the pump chamber thus escapes through this passage as the piston moves down inside the pump body.
This downwards motion stops when the bottom end of the skirt 8 comes into abutment against the bottom 1a of the pump body. The pressure in the pump chamber reduces because piston motion has stopped, thereby causing the channel 3a to be closed by the plug 7 which is again pressed resiliently against its seat 7a by the spring 10.
When the user releases thrust on the rod 3, the spring 10 returns the valve 6 upwards, taking with it the piston 2. At the beginning of this upwards motion, the pump chamber 12 is isolated by the skirt 8 fitting over the tubular endpiece 4 and by the plug 7 being pressed against its seat 7a. The upwards displacement of the piston 2 thus creates suction. When the piston 2 comes into abutment against the ferrule 11, the skirt 8 disengages from the endpiece 4, thereby opening the annular passage 13. Because of the suction in the pump chamber 12, the substance contained in the dip tube 5 and in the receptacle is sucked into the pump chamber, which is thus filled again.
The inside sealing lip 8b formed at the bottom end of the skirt 8 could be replaced by an outside sealing lip formed on the top end of the tubular endpiece 4.
Instead of the skirt 8 fitting over an endpiece 4 projecting from the bottom 1a of the pump body, the pump could have a pump body side wall including a cylindrical bottom portion of smaller diameter above the bottom 1a and in which a cylinder integral with the valve member 6 is received. In which case a sealing lip could be provided either on the smaller diameter bottom portion of the pump body or on the cylinder integral with the valve member 6, for the purpose of improving the sealing between these two parts when fitted together.
Other variants of this type of pump are known to the person skilled in the art.
The pump of the type described above may be used with a receptacle that is closed in sealed manner and in which the substance to be sprayed or to be dispensed is maintained under pressure by a dissolved gas (freon) or by a non-dissolved gas (nitrogen). The purpose of the gas may be to keep the substance out of contact with the atmosphere so as to avoid it being polluted or oxidized. The gas may also serve to facilitate pump priming and to ensure that the pump chamber is filled more completely and more quickly. When the gas is used in this way, it is difficult to inject the propellant gas into the receptacle after said receptacle has been filled with substance and the pump has been installed and fixed in place.
One solution to this problem is proposed in French patent No. 2 620 052 granted to Valois, European patent application EP-0 307 310 and U.S. Pat. No. 4 964 547. The endpiece 4 is provided with external projections 14 close to the bottom 1a of the pump body, as shown in accompanying FIG. 2. To inject a gas into the receptacle, a needle is inserted down the channel 3a of the rod and pressed against the plug 7 of the valve member 6 with sufficient force to lower the valve member inside the pump chamber and cause the sealing lip 8b to ride up onto the external projections of the endpiece. In normal use, the force exerted on the rod 3 by a user is not sufficient to move the sealing lip 8b onto the projections 14. The plug moving away from its seat 7a releases a first passage between the pump chamber and the channel 3a, and moving the sealing lip 8a onto the external projections 14 of the endpiece releases a second passage between the pump chamber and the receptacle. The gas can then be injected into the receptacle via the channel 3a.
That solution suffers from several drawbacks. Firstly, it requires a special gas filler head including a needle for pressing down the plug 7. Such filler heads are more difficult to position and more expensive than conventional filler heads that do not include a needle.
In addition, pushing the sealing lip 8b onto the projections 14 causes the sealing lip 8b to be subjected to considerable stress and this may give rise to plastic deformation that damages the sealing provided by said lip 8b.
Finally, to facilitate engaging the needle on the plug 7, the plug 7 is generally made relatively long so that its seat 7a is close to the top end of the rod 3. Since the valve member 6 is generally made all in one piece, out of a material that is relatively flexible such as low density polyethylene, such a long plug 7 may give rise to large amounts of plastic or elastic deformation during successive occasions the pump is actuated. Such deformation changes the position of the valve member 6 relative to the piston 2 and to the rod 3, thereby changing the quantity of substance that is delivered each time the pump is actuated.
It may also be advantageous for the pump chamber to be put into communication simultaneously with the receptacle and the channel 3a, not for the purpose of injecting a gas into the receptacle, but in order to establish suction to prime the pump and cause the substance to move up from the receptacle into the pump chamber, and/or for the purpose of removing undesirable gases from said substance. This can be achieved using the apparatus of the above-mentioned Valois patent, with the drawbacks already mentioned.